Process of manufacturing electric insulating-sleeves.



E. HAEFELY.` 'PROCESS 0F MANUFACTURING E'LECTRC INSULATING SLEEVES.

I -APPLICATION *FILED AUG.5, |916.. V 4 v 1,237,93 1 Patented Aug. 1.4, 1917.

lNvENTar-', 'l/wn.. HAEFELY' EMIL IIAEEELY, or RASEE, SWITZERLAND.

PRoCEss 0E MANUFACTURING ELECTRIC INsULAfrINGLsLEEvEs.

Specification of Letters Patent. Patentd Aug, 14, 1917,

Application filed August 5, 1916. Serial No. 113,312. 'l

To all whom t may concern:

Be it known that I, EMIL HAEFELY, a

citizen of the Swiss Republic, and resident of Basel, Switzerland, have invented new and useful Improvements in Process ofy Manufacturing Electric Insulating-Sleeves, of which the following is a full, clear, and exact specification.

The employment of hard press-paper sleeves for insulation purposes in transformers is already known.

In the construction of transformers of.

modern types the windings are by preference fitted in annular form over the iron cores which, in order to adapt themselves to this form, are of rectangular or cruciform cross section. The low tensign winding usually surrounds the core while the high tension winding surrounds the low tension wind-V ing, the latter being suitably insulated both internally and externally. Between the low and high tension windings insulation of i high resistance corresponding to the difference of potential, is absolutely necessary; this insulation is generally constructed of hard press-paper cylinders of the requisite thickness which combine with very high insulating value the advantages of exact dimensions and high mechanical rigidity.

Between the low tension winding and the iron however such a high resistance insulation is not generally necessary as the difference in potential is only comparatively low. Notwithstanding this however, a few factories employed hard press-paper cylinders in this position also in view of the convenience of erection and greater security, but of course they used cylinders of the smallest possible' thickness. For reasons of manuf facture however this thickness 'cannot be less than about 3 mm. so that the required degree of insulation is without necessity considerably exceeded and the cost of construction correspondingly increased. For the latter reason other manufacturers employ a more inferior insulating material for this purpose, for example sheets of pressed J paper and the like are placed around the iron core. The resistance to penetration or breakdown of such materials is entirely sufficient for the purpose in view at the commencement; most of these materials have Vhowever all kinds of undesirable properties,

such for example as liability to absorb moisture and so forth, so that it would be desirable t0 avoid their use in transformers if tubular body.

For higher tensions the insulation sleeve the approved hard press-paper could be pro-Y duced more cheaply. v 1

The present invention relates to a process of manufacturing insulation sleeves of'variable diameter, of hard press-paper, especially adapted for insulating purposes 'in transformers.

The insulation sleeves to be manufactured.

consist in the simplest form of at least one thin-walled tubular body of woundv presspaper which is cut longitudinally and is under suiiicient stress to cause the adjacent edges to overlap. In consequence of this construction the insulation sleeve can easily be forced into the required shape which it must have in a transformer and it is unnecessary to construct a sleeve of suitable dimensions for every individual case. For low and middle` tensions it is recommendable to employ atleast one single sleeve or is preferably composed of a number of suchv tubular bodies which are inserted one inside another in such a manner that Vtheir lon! gitudinal cuts are relatively displaced, ,the joint in one being covered by the solid portionof another tubular body. The num ber of tubular bodies used in this .way

depends upon the potential which thev sleeve must be capable of withstanding. The tubular bodies may also be employed for a vgreater as well as for a smaller'diameter than corresponds to their manufacture, inasmuch as they are slightly widened in the first case and slightly compressed with overlapping in the secondcase.

The improved process of manufacturing the insulating sleeves set forth consists in passing a web of papercoated with ad" hesivel through a winding machine so as to wind up the separate layersand to cause them to stick together under pressure; each time after having thus united a determined number of layers to form a tubular body, a

separating web or layer free from adhesive is which constitutes a unit from a manufactuu ing point of View, and does not cause any difficulties in manufacture, whereas the thinwalled tubular bodies which have hitherto come into consideration as insulation sleeves can only be produced separately with diificulty and not of good quality. Furthermore, the said cylindric bodies may be stocked in the greatest sizes of maufacture and used afterward by being rolled up moreI or less, being thus brought into the cylindr-ic shape required in any particular case.

In viewer Vthe present invention it is possible to employ hard press-paper, which is valued in consequence of its insulating capacity, and to make it comparatively cheaply inthe required thickness and oi' good quality. It can therefore be used for example as insulation between two members of a trans former, as already hereinbefore described, either by pressing a cut tubular body to a smaller radius of curvature so as to cause the adjacent edges to overlap, which is easily possible in view of the inherent springiness of the tubular body, or by inserting two or more of the tubular bodies, according to the potential they are required to withstand, coaXially one within another in such a manner that the longitudinal slot of one is covered by the solid portion of the next inner or outer tubular body.

Obviously, the present invention is not only convenient for insulating purposes in transformers, but also as insulation on pole cores and the like, as well as for any insulating purposes in electric devices. lFurther, the cut tubular bodies which are thinwalled and Flexible, although being obtained upon a mand-rel of circular cross section, may also be employed upon cores, branches, 'bobbins and the like of any other form of transverse section, such as polygonal, oval, rectangular, square, etc.

The accompanying drawing shows three examples of the improved insulating sleeve; Figure l is a cross section of a sleeve composed of one single tube in use upon a transformer core; Fig. 2 isa cross section of a sleeve com-posed of two concentric tubes and Fig. 3 is a cross section of a sleeve composed of three concentric tubes.

According to l, the insulating sleeve represented is composed of one single thinwalled tubular body a, of wound-on or coiled press-paper, the layers of which are irmly united together by sticking and under pressure. |The so formed body or tube is cut or split at over its whole length and owing to its form and texture, it is springy or elastic within certain limits so as to allow its adjacent edges to overlap when it must be reduced in diameter, as represented.

Fig. 2 shows an insulating sleeve coinposed o two thin-walled tubular bodies, c, cl of wound press-paper, cut over their whole length and each of which has its edges overlapped. The said tubular bodies c, d are concentrically arranged and so placed relatively to each other that ltheir longitudinal slots and overlapping parts are angularly displaced, so that the slot of one is covered by a solid uncut portion of the other tubular body.

In Fig. 3 an analogous concentric arrangement is shown with three tubular bodies'c, f, g of wound press-papenpcut over their whole length, but wherein the edges of each tubular body are not overlapped, but at some distance from each other, as shown, according to the greater diameter required for the insulating sleeve.

A process of manufacturing longitudinally sli-t, springy insulation sleeves'of variable diameter, of hard press-paper, consisting in mechanically winding up under pressure a web of paper coated with adhesive so as to unite the separate layers under pressure, and each time after having thus united a certain number of layers to form a tubular body, causing a separating web or layer free from adhesive to be wound on so as to my name this 3d day of July,vl916, in the4 presence of two subscribing witnesses.

EMIL HAEFELY. litnesses Anyonel ZUBER, AMAND BRAUN.

Gopies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington. D. C. I 

